Astronauts Performing Third and Final Spacewalk

At 8:24 a.m. EST, STS-129 spacewalkers Robert Satcher and Randy Bresnik switched their suits to battery power, signaling the start of the mission’s third and final outing. Atlantis Mission Specialist Mike Foreman will be inside the International Space Station serving as the choreographer and relaying communications from Mission Control in Houston.

Satcher and Bresnik are scheduled for a six and a half hour spacewalk, although 30-45 minutes of it are set aside as “contingency” time for any tasks that require longer to complete than estimated. Because the mission’s first two spacewalks accomplished more than was planned, this third excursion has taken on several new chores that originally were listed as mission “get ahead” tasks.

The first item on Satcher’s agenda is to transfer an oxygen-filled high pressure gas tank (HPGT) from the External Logistics Carrier (ELC) 2 to the Quest airlock. Space station robotic arm operators Leland Melvin and Barry Wilmore will assist with the move of the large, “doghouse” shaped HPGT. While Satcher works with the HPGT, Bresnik will retrieve the Materials International Space Station Experiment (MISSE 7) from Atlantis’ payload bay and install it on ELC 2. The pair will work together to remove Quest airlock debris shields and activate the HPGT. The tank will be used to replenish airlock air that’s lost when spacewalkers exit and enter Quest..The HPGT installation is expected to take about three hours.

Next, while Satcher loosens a bolt on a starboard truss Ammonia Tank Assembly, Bresnik will install fluid jumpers on the Port1/Port 3 and Starboard 1/Starboard 3 truss segments. Finally, while Bresnik relocates an articulating portable foot restraint, Satcher will install two camera covers and an insulating sleeve on the station’s Mobile Base System.

This is the 230th spacewalk conducted by U.S. astronauts, the 136th in support of space station assembly and maintenance, the 100th out of space station airlocks, and the second for both Satcher and Bresnik. Satcher is wearing an all white spacesuit and his helmet cam displays number 16. Bresnik is wearing a spacesuit with broken red stripes and his helmet cam displays number 18.